A two-dimensional numerical model for syngas production from tri-reforming of methane (TRM) in adiabatic tubular fixed-bed reactors was established. From the results obtained, it was found that reactant must be preheated to certain temperatures for TRM activation. Although the delay factor accounting for the varying catalytic bed activities produced different temperature and species mole fraction profiles in the reactor upstream, the reactor performance was delay factor independent if the reactor outlet results were used because nearly identical temperature and species mole fraction variations were obtained at the reactor downstream. The numerical results also indicated that reverse water-gas shift reaction plays an important role for H-2 and CO yields. With higher O-2 in reactant, high temperature resulted, leading to lower H-2/CO ratio. The absence of H2O in the reactant caused dry reforming of methane as the dominant reaction, resulting in H-2/CO ratio close to unity. With the absence of CO2 in the reactant, steam reforming of methane was the dominant reaction, resulting in H-2/CO ratio close to 3. Using flue gas from combustion as TRM feedstock, it was found that H-2/CO ratio was enhanced using lower CH4 amount in reactant. High-temperature flue gas was suggested for TRM for the activation requirement. (C) 2016 Elsevier Ltd. All rights reserved.